Solar cells attracting an attention as a clean energy source have been used for ordinary houses in recent years; however, they have not yet been widely spread. The reasons therefor include that the module is obliged to be enlarged because the performance of a solar cell itself is hardly excellent enough, that the productivity in manufacturing the module is low, that as a result the solar cell itself becomes expensive, and the like.
Graetzel (Switzerland) et al. developed a photoelectric (solar) cell using a photoelectric conversion device called a dye-sensitized solar cell in 1991. This is also called a Graetzel cell comprising: a thin film substrate serving as one electrode, the thin film substrate being sensitized with a dye on a transparent conductive substrate and composed of oxide semiconductor microparticles; a substrate comprised of a counter electrode, the counter electrode being arranged with a reducing agent such as platinum, the substrate being arranged so as to face the thin film substrate; and a charge transfer layer (electrolyte containing a redox material) interposed between the thin film substrate and the substrate. Here, adsorption of a ruthenium complex dye to a porous titanium oxide electrode has permitted this type photoelectric cell to have a performance close to that of the silicon solar cell (non-Patent Document 1). However, for the purpose of practical application of the dye-sensitized solar cell, exhibiting high efficiency and improving durability in a large-sized practical cell are essential, and thus there has been a need for improvement from these aspects.
With regards to injection of a charge transfer layer in a general dye-sensitized solar cell, a method for injecting this from an injection port as shown in FIG. 1 is used for preparation of the dye-sensitized solar cell. That is, in the method in FIG. 1, two injection ports used for injecting a charge transfer layer are opened in one of conductive supports in advance with an atmospheric injection method utilizing capillary phenomenon, and then the charge transfer layer is injected from the injection ports after bonding both conductive supports together with a sealing agent, and subsequently the injection ports are sealed using a sealing agent. For the charge transfer layer of the dye-sensitized solar cell prepared in this way, an iodine-based electrolyte pair dissolved into an electrolyte solvent, such as an electrochemically stable organic solvent, is used. However, in such electrochemical conversion device, the charge transfer layer, for example, erodes the cured sealing agent layer during a long period of operation or storage, so that the charge transfer layer will leak or be depleted. For this reason, such electrochemical conversion device has the disadvantage of being impractical for use because the photoelectric conversion efficiency drops significantly or the electrochemical conversion device will not function as the photoelectric conversion device.
In addition, since the above-described method comprises a step of manufacturing an empty cell once, a step of injecting a charge transfer layer, and a step of sealing an injection port, it may generally require a long hours of work and have limited productivity of the photoelectric conversion devices. That is, if the step of manufacturing an empty cell and the step of injecting a charge transfer layer among the above-described steps can be continuously carried out, it is convenient in exhibiting high productivity of the photoelectric conversion devices. However, generally, an isobutylene resin-based sealing agent used in the photoelectric conversion devices, which are prepared using an “electrolyte solution dropping method” shown in the present application, lacks of the adhesive strength, while in the case of the photoelectric conversion devices using a sealing agent that is used in a liquid crystal, the leakage and the like of an electrolyte solution containing iodine is an issue. At present, a high-performance sealing agent used for the photoelectric conversion devices that can clear all these problems has not been found yet.
Under such situation, a photoelectric conversion device using a solid electrolyte pair, and also a photoelectric conversion device containing a solid electrolyte pair using a crosslinked polyethylene oxide-based high molecular compound have been proposed in Patent Document 1 and non-Patent Document 2, respectively. However, the photoelectric conversion devices using such solid electrolyte pair have poor photoelectric conversion characteristics, in particular, an insufficient short circuit current density, and additionally have insufficient durability. Moreover, in order to prevent the leakage and depletion of the electrolyte solution and improve its durability, there have been disclosed methods for using a pyridinium salt, an imidazolium salt, a triazonium salt, or the like as the electrolyte pair salt (Patent Document 2, Patent Document 3). Such salts are in a liquid state at room temperature, and are called a room temperature molten salt. Even with this method, the cell photocurrent will gradually decrease due to the leakage or depletion of the charge transfer layer, so that sufficient durability cannot be obtained.    Patent Document 1: JP-A-07-288142    Patent Document 2: WO 95/18456    Patent Document 3: JP-A-08-259543    Non-Patent Document 1: Nature, vol. 353, 1991, pp. 737-740    Non-Patent Document 2: J. Am. Chem. Soc. 115 (1993) 6382